Positive displacement pumps, in which peristaltic pumps form a subclass, are employed for pumping problematic substances in particular, such as abrasive, corrosive, slurried or high-viscosity liquids and liquid-suspended solids. Peristaltic pumps are also preferred when pumping as a primary function must be complemented with accurate metering, high hygienic standard and leakproofness. Peristaltic pumps are used widely e.g. in the manufacture of foodstuffs, drugs, oil and chemical products. In heavy industries, peristaltic pumps serve to pump, inter alia, such materials as liquids and ore/mineral suspensions.
To operate properly, a peristaltic pump must be capable of forcing a volume of a fluid medium to move along a hose/tube by way of peristaltically compressing the hose from end to end during one turn of the pump rotor while simultaneously the next fluid volume is already filling the hose. Conventionally, this pumping sequence is implemented by rotating a nonrotary shoe or pressing roller, whereby the hose is subjected to progressive compression in the nip between the shoe/roller and the peripheral wall of the pump head. Furthermore, the hose/tube/tubing is selected to be sufficiently elastic and reinforces such that the hose resumes its circular profile immediately after the compression thereby creating a vacuum in its lumen thus including the entry of the next volume of the fluid medium into the hose.